Back in 1994 I co-authored a book on modelling with my colleague John Daniels.  We called our approach “Syntropy”.  The book has been out of print for several years now.  Sales were modest, but it was quite influential.  The Object Constraint Language, which was developed at IBM by my team when I worked there later in the 1990s ended up as part of the UML and was heavily influenced by ideas from the book.

John has now made the book openly available online at http://www.syntropy.co.uk/syntropy/designing-object-systems.pdf.  Please let me know if you have a look, and what you think.